Absorbent products useful as high performance wipers are known in the art. U.S. Pat. No. 6,890,649 to Hobbs et al. (3M) discloses polyester microfibers for use in a wiper product. According to the '649 patent the microfibers have an average effective diameter less than 20 microns and generally from 0.01 microns to 10 microns. See column 2, lines 38-40. These microfibers are prepared by fibrillating a film surface and then harvesting the fibers. U.S. Pat. No. 6,849,329 to Perez et al. discloses microfibers for use in cleaning wipes. These fibers are similar to those described in the '649 patent discussed above. U.S. Pat. No. 6,645,618 also to Hobbes et al. also discloses microfibers in fibrous mats such as those used for removal of oil from water or their use as wipers.
United States Patent Publication No. US 2005/0148264 (application Ser. No. 10/748,648) of Varona et al. discloses a wiper with a bimodal pore size distribution. The wiper is made from melt blown fibers as well as coarser fibers and papermaking fibers. See page 2, paragraph 16.
United States Patent Publication No. US 2004/0203306 (application Ser. No. 10/833,229) of Grafe et al. discloses a flexible wipe including a non-woven layer and at least one adhered nanofiber layer. It is noted on page 1, paragraph 9 that the microfibers have a fiber diameter of from about 0.05 microns to about 2 microns. In this patent, the nanofiber webs were evaluated for cleaning automotive dashboards, automotive windows and so forth. For example, see page 8, paragraphs 55, 56.
U.S. Pat. No. 4,931,201 to Julemont discloses a non-woven wiper incorporating melt-blown fiber. U.S. Pat. No. 4,906,513 to Kebbell et al. also discloses a wiper having melt-blown fiber. Here, polypropylene microfibers are used and the wipers are reported to provide streak-free wiping properties. This patent is of general interest as is U.S. Pat. No. 4,436,780 to Hotchkiss et al. which discloses a wiper having a layer of melt-blown polypropylene fibers and on either side a spun bonded polypropylene filament layer. See, also, U.S. Pat. No. 4,426,417 to Meitner et al. which discloses a non-woven wiper having a matrix of non-woven fibers including microfiber and staple fiber. U.S. Pat. No. 4,307,143 to Meitner discloses a low cost wiper for industrial applications which includes thermoplastic, melt-blown fibers.
U.S. Pat. No. 4,100,324 to Anderson et al. discloses a non-woven fabric useful as a wiper which incorporates wood pulp fibers.
United States Patent Publication No. US 2006/0141881 (application Ser. No. 11/361,875) of Bergsten et al. discloses a wipe with melt-blown fibers. This publication also describes a drag test at pages 7 and 9. Note, for example, page 7, paragraph 59. According to the test results on page 9, microfiber increases the drag of the wipe on a surface. United States Patent Publication No. US 2003/0200991 (application Ser. No. 10/135,903) of Keck et al. discloses a dual texture absorbent web.
U.S. Pat. No. 6,573,204 to Philipp et al. discloses a cleaning cloth having a non-woven structure made from micro staple fibers of at least two different polymers and secondary staple fibers bound into the micro staple fibers. The split fiber is reported to have a titer of 0.17 to 3.0 dtex prior to being split. See Col. 2, lines 7 through 9. Note, also, U.S. Pat. No. 6,624,100 to Pike which discloses splitable fiber for use in microfiber webs.
While there have been advances in the art as to high efficiency wipers, existing products tend to be relatively difficult and expensive to produce and are not readily produced on conventional high speed papermachines. Furthermore, products with mixtures of pulp-derived papermaking fibers and synthetic fibers tend to lack strength, especially wet strength, because of poor interfiber bonding. Wipers of this invention exhibit surprising wet strength and are economically produced on conventional equipment such as a CWP papermachine.